Chronic bromide intoxication can produce a schizophrenia-like syndrome in man. To determine which structures in brain might be involved, we are studying local cerebral glucose utilization (LCGU) with the [14C]deoxyglucose method in rats being administered bromides chronically in the drinking water for up to 10 days and in both the water and by osmotic pump for up to 49 days. In rats given bromides only in the drinking water serum bromide levels were raised to about 200 mg NaBr/l in 2 days, 400 mg/l in 6 days, and 425 mg/l in 10 days. In control rats given only water serum bromide levels were between 0 and 12.3 mg/l. In rats given bromides in both drinking water and by osmotic pump serum bromide levels averaged 420 mg/l by 14 days, 540 mg/l by 21 days, 540 mg/l by 35 days, and 525 mg/l by 49 days. In control rats serum bromide levels ranged between 0 and 59 mg/l. Average rates of glucose utilization in the brain as a whole have thus far been determined in 34 rats. In rats treated for 21 days with bromide rates of glucose utilization were decreased by 12.5% compared with controls (p<0.05), grouped t-test). Densitometric analyses and image-processing of the autoradiograms needed to obtain rates of glucose utilization in individual regions of the brain are very labor-intensive procedures, and because of the considerable loss of personnel that we suffered during the past two years, we have been compelled to suspend this project, temporarily we hope.